[Помогите] how to add group of keyword

i need to add group of keyword.
need url like site.com/group-keyword
i try add below code in controller/seo_url.php

$url .= '/' . $query->row['keyword'];

change to

$url .= '/' . $query->row['group'] . '-' . $query->row['keyword'];

the url is go to
site.com/group-keyword. url it true.
but it not work.
the page it go to 404 page.